1. Field of the Invention
This invention relates generally to the field of electrostatic copying machines of the type which utilize a dry toner developing material to render visible an electrostatic latent image produced on a photoconductive recording medium. More particularly, the invention relates to an apparatus for periodically replenishing the supply of the dry toner developing material stored in the copying machine where the supply of developing material has been depleted to a low volume from normal use of the copying machine.
As is well known in the field today, the typical electrostatic copying machine which operates on the xerographic process includes a photoconductive member on which a latent electrostatic charge image of graphic information on an original document is created by selective discharge of a uniformly charged photoconductive member. The latent image is rendered visible by applying thereto a suitable electrostatic marking material such as dry toner developing material, after which the visible toner image is transferred to a sheet of paper and is permanently affixed thereto by suitable means, usually heating.
The developing material used in most present day electrostatic copying machines consists of a very finely ground carbon base powder which is extremely difficult and messy to handle, and is difficult to clean from machine parts, hands and clothing. Because of its very fine nature, it is difficult to pour from a bottle because it bridges at the neck of the bottle, thereby requiring a certain degree of shaking or rolling of the bottle or other agitation of the powder. In addition, pouring dry toner powder from a bottle or package into the storage receptacle of a copying machine is undesirable for the reason that inevitably carbon toner dust rises as a cloud and both settles on adjacent machine parts and is carried out into the room through vent fans or other openings. As toner dust accumulates on the mirrors and lenses of the optical system in the copying machine, the quality of the copy degrades and ultimately becomes unacceptable if these machine parts are not periodically cleaned. Further, any accumulation of toner dust, even in minute quantities, in any of the sensitive electronic control components of the copying machine can easily result in malfunctioning of the machine which normally requires servicing beyond the capability of the operator. Also, toner which may either contact an operator's hands or get on his clothing is very difficult to remove and often permanently stains certain materials. Another serious problem is that the toner dust, if inhaled in even small amounts, may cause respiratory tract irritation resulting in coughing and sneezing, which may have serious consequences for anyone with chronic respiratory conditions.
It is apparent from the foregoing that there exists a variety of troublesome and in some cases serious problems which result from handling dry toner developing materials in a conventional manner, such as by pouring directly from a bottle into the toner storage receptacle of the copying machine. Nevertheless, because of the gradual consumption of the developing material during the copying process it must be periodically replenished.
2. The Prior Art
The most common solution to the above problems is to provide a containerized system for periodically replenishing the dry toner developing material. There are generally two types of containerized systems currently in use, in one of which the toner material is stored in a bottle or other container mounted in a suitable receptacle, and a dispensing device is provided in the bottle or other container for metering the flow of toner material from the bottle to a storage receptacle in the copying machine at a suitable rate depending upon the rate of consumption of the toner material during the copying operation. Such a system is shown in U.S. Pat. No. 3,853,246, a principal disadvantage of which is the relatively high expense of the bottle with the dispensing device therein, since the bottle is not reused after it becomes empty.
The other and more preferable type of containerized system, as shown in U.S. Pat. Nos. 4,237,943 and 4,304,273 includes a container having suitable means for sealing the toner material therein until it is ready for use, the container and copying machine having cooperating means for mounting the container on the copying machine so that the toner merely falls by gravity into a storage receptacle in the copying machine. Preferably the sealing means is such that it is removed after the toner bottle is in place in a dispensing position. One disadvantage with the system shown in the U.S. Pat. No. 4,237,943 is that it is necessary to physically handle a closure member which is in contact with toner material in order to open the container, thus leaving the possibility that some toner may be deposited on machine parts or the hand or clothing of an operator.
A significant disadvantage of the device shown in the U.S. Pat. No. 4,304,273 is that the dispensing opening from the bottle is so small that the developing material has a tendency to bridge thereby requiring agitation of the bottle which tends to raise a cloud of developing material which settles on adjacent machine parts.